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banding... more complex the longer i work on the t

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  #1  
Old 12-06-2008, 05:23 PM
tomasz.k tomasz.k is offline
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banding... more complex the longer i work on the t

Hi all,

I'm new on the forum, so sorry if this topic is covered in full somewhere but I did look around and did not find a real answer.

We often have problems with banding in our studio. I'm sure we're not the only ones around... Sometimes we manage to cope with it quite quickly and easily, but there were times when we really were desperate for better methods as the deadline was mercilessly close and we really couldn't come up with a proper solution.

Underneath I will try to list the methods I usually try to use to cope with the problem as well as a few thoughts on the nature of the problem. I really do hope that there is whole bunch of people here who will efortlessly solve my headache;)


1. Upon seeing banding on screen I usually first look through seperate RGB and later Lab channels to see how it is constructed.

2. If it happens to be simple color banding (which means it isn't visible on the L channel but just on ab in Lab) then of course removing it is a snap. Solutions would be numerous: paint over with a color layer, blur sections of a and b channels....

3. If this is not the case, if I have been working on an 8bit file and have the raw, then I try to redevelop in 16 bit and see if this helps. Rarely it is a solution, but it helps a bit in may cases. (And often it is a question of small steps to get rid of it completely.)

4. Lets assume that 16bit developing didn't help and I'm stuck with my 8bit file. Also that the photographer does not want to alter the image look so I can not just redo the background by making a new gradient with a different graininess and color. What next then:

5. All of the steps underneath should work better if done in 16bit, at least in theory;)

6. Sometimes if it is just one place where the uneven transition is visible painting on a color layer helps to at least partially get rid of the effect. Then we can for instance even out the difference in luminosity by using dodge and burn lets say through a softlight layer.

7. Another trick is to (of course) add grain to that section and then reduce it through median or reduce noise on seperate layer which is a copy of the section, place it on top and set it as a luminosity layer, then duplicate it and set it as a color layer. Then reduce opacity of the layers to the desired effect, mask edges or fragments....

8. Copying the banding section and taking it to Lab and blurring the color channels and then evening out the L channel with dodge and burn and taking back to RGB and placing on top and then setting this at the proper opacity also often helps.

9. If the problem is clearly visible on one or more fo the seperate RGb channels sometime delicate dodge and burn, healing brush (etc) operations help.

10. If it is not affecting large areas sometimes just healing the images in the areas affected can break up the lines...

11. Creating a color layer and healing, stamping from nearby areas to create an even tone and then if it is also a luminosity problem healing on a luminosity layer can work

12. Making tons of circular gradients of tone very close or even picked from the affected place, and using them on very low opacity creates a gradient with a structure so complex that banding line don't appear. Sometimes this helped me a lot.

13. If things get really bad I do sometimes try to just create that section from scrap and then recreate the grain or structure of the image, but this is not really a solution. It's just a way around the problem which in most cases would use up too much time or just be impossible.


What is really bothering me though is that the banding we see on screen is sometimes not visible on the actual output file. We recently did a cover for a magazine; the image was "almost" bw, in fact it was a RGB but developed with ) saturation but with channel clipping in Capture One(channel B was taken down to around 245 from what I remember, which gave the image a nice yellowish tone) which resulted in very subtle color variantions. The file was already developed with the clipping so it was not a question of 8bit curve manipulation in ps. In the shadows there were visible green banding lines.

Now THIS is what bothers me: the photographer saw it in different places then we did. We changed the color to an even tone in the whole section and it was still visible there but the look changed (the color picker suggested though that our monitors are fooling us). We began to suspect that this is a software/ hardware rendering problem so we proofed it. There was no banding there.... My theory is that sometimes banding shows in places were it actually is not present, just the software/ hardware rendering shows it due to inadequate hardware color rendering possibilities.

Still it does not change the fact that even if the banding is not physically there a retoucher has to remove the appearence of it to make the photographer happy;)

Sorry for the long post. What do you think?
Tomasz

tk@houseofretouching.com
www.houseofretouching.com
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  #2  
Old 12-06-2008, 10:11 PM
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TommyO TommyO is offline
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Re: banding... more complex the longer i work on t

Tomasz,
Welcome to RetouchPro ! Sorry about your problem, it sounds very irritating.

It also sounds like a mixture of three issues.
(a) low bit depth; (b) broad color space - hungry for more bits; (c) operating system bugs.

A few questions:
What color profiles are you using ?
Are you working in a Mac environment ?
Are you up to date on OS patches ?
Are your video drivers up to date ?
And your client/photographer... same questions.

The MAC OS was having similar issues in 2005-2006. Since then many of those have been patched up. The fact that you are not seeing it in proof also makes me lean this way.
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Old 12-07-2008, 10:46 AM
tomasz.k tomasz.k is offline
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Re: banding... more complex the longer i work on t

Hello Tommy,
Glad to see you have some clues although I do not really think this could be an OS issue, but I am more than open to such a possibility.

Do you use any other methods for removing banding though?

Answers underneath:

What color profiles are you using ?
We work in Adobe 1998, monitors calibrated with Eye One
Are you working in a Mac environment ?
Yes Leopard
Are you up to date on OS patches ?
up to date with everything
Are your video drivers up to date ?
Not sure, but we see the same thing on a G5 and MacPro, so I don't think it's a video card driver problem
And your client/photographer... same questions.
He was working on a Macbook Pro with an external monitor, don't know what kind though


I also have one more possible solution, could it be that we are still using LCD's which have 12bit hardware and not 16bit? We still use NEC MultiSync® LCD2190UXi monitors at the moment, but want to upgrade to Eizo CG series when the opportunity arises.

I think when I will have a moment tomorrow I'll crop that part of the cover and post a link to see if you see banding in the same spot.
Cheers
Tomasz
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Old 12-07-2008, 03:03 PM
HuBBa HuBBa is offline
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Re: banding... more complex the longer i work on t

I would personally say this is most likely hardware related, especially since you say that you see banding in different areas than the photographer/client do on their equipment.

So to avoid it, get as high quality gear as you possibly can. If budget don't allow for the better Eizo screens, use prints (from a GOOD printer) as references. Its slower but generally the end media where you bother with banding issues is print anyway. Web and banding issues is like worrying about hi-fi sound mixing on a mp3 player
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  #5  
Old 12-07-2008, 04:49 PM
tomasz.k tomasz.k is offline
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Re: banding... more complex the longer i work on t

Quote:
Originally Posted by HuBBa View Post
I would personally say this is most likely hardware related, especially since you say that you see banding in different areas than the photographer/client do on their equipment.

So to avoid it, get as high quality gear as you possibly can. If budget don't allow for the better Eizo screens, use prints (from a GOOD printer) as references. Its slower but generally the end media where you bother with banding issues is print anyway. Web and banding issues is like worrying about hi-fi sound mixing on a mp3 player
Yes that is true, but this was just one occurrence. Usually we see banding in the same areas and more then often it does come out in print.
My general question was though do you have any other methods of dealing with the banding?
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Old 12-07-2008, 05:11 PM
HuBBa HuBBa is offline
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Re: banding... more complex the longer i work on t

Ah sorry. should have written a bit more.

If the banding shows up in print, then the dynamics have been compressed somehow. This usually happens when using certain tools like curves which re-shapes the range of tones. Its as you have noticed already very hard to avoid, and re-painting in a smooth gradiant can be pure hell.

I'm personally no expert on which tools compresses tonal ranges but if im not mistaken, the obvious ones are curves, levels, and hue/saturation. So avoid using those on smooth gradient areas as banding will most likely occur.

What im not however 100% sure is how much compression is done if curves/contrast adjustments are done on the RAW original before going into normal pixel-manipulation.

This is discussed a bit in a video called Adobe Photoshop Cosmetic Techniques (http://www.thestudio2u.com/etntworld) but there ought to be some info about this on the net aswell. It's mostly evident with tools that affect the entire tonal ranges ofcourse, so colorbalance, hue/sat, curves, levels, etc. and blendmodes will effect this.

The way to avoid it (as i see it as a photographer) is to start of with as perfect exposure as possible, which will need as minimal tweaking afterwards. Since once you start messing with tonal ranges, banding may occur. And ofcourse going with as high of a bitdepth as you can in the original files.

Sorry if this isnt much help to what you already know but its a problem i battle with aswell.
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Old 12-07-2008, 05:34 PM
tomasz.k tomasz.k is offline
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Re: banding... more complex the longer i work on t

I totally agree with you. We do try to do as much as possible through raw manipulation. Still photographers often ask us to push the raw VERY far, so although we develop to 16bit we end up with banding from the beginning...
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Old 12-08-2008, 12:15 AM
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stopa stopa is offline
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Re: banding... more complex the longer i work on t

This is the worst nightmare for us... And I think that it is our faith... Since Newton rings appears, on the first enlarged prints.

first of all - Thanks for your post. Now I know that not only I fight with this - and it is not only my paranoia. I thought, maybe I don't know something and I have some holes in my knowledge?

Tomasz- why you work on LAB? Every time you convert to other space (RGB or CMYK) all gradients are re-counted - and ALWAYS bad things happen to all gradients.
(you can trap final step as smart object - then convert it)

Yours banding - more known as Moire, or Tonal pass - it is a matter of bit depth.
And I will try to illustrate it for others.
We have 256 steps on 8 bit for each channel. it is far enough when you have color-full image, like parrot sitting on a triangle. But we often work with semi-tonal images. Almost white skin, and very dark - black - background.
Now you know that you have not AS much space! Only well balanced colours are neutral. So you now have only few bit left to work on!
And now we are going further: Background
You have 5000(+) pixels high image, but you NEED totally smooth gradient - but wait... DARK - gradient! Now you have only 15-50 steps for this!
(take a sample for lightness on background - "L" indicate values from 0 to 30...)
Once again: it is simple arithmetic 5000 pixels in 50 steps - each step is 100 pixel high! What happens when you have only 5-to-15 background lightness? And mathematics never fails... sorry...

My solution is dodge and burn, and blur and noise.

Don't even think that 16bits will help you out with this... CMYK is only 6bit or even less (0-100% of ink for each channel)... and our work is often finally converted for it.
Dan Margulis said - that it is essential to build gradients in the final color mode.

- Tell as more about - if your bands was shown on proof, or on display?
- I may say that apple displays are waste of money (you can pass it to your client)
- Show this image to us, I am really curious.

And finally - welcome to RetouchPro!
Fajnie że się spotykamy właśnie tu na retouchPro Pozdrawiam W

Last edited by stopa; 12-08-2008 at 01:58 AM.
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Old 12-08-2008, 01:57 AM
tomasz.k tomasz.k is offline
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Re: banding... more complex the longer i work on t

Quote:
Originally Posted by stopa View Post
Tomasz- why you work on LAB? Every time you convert to other space (RGB or CMYK) all gradients are re-counted - and ALWAYS bad things happen to all gradients.
(you can trap final step as smart object - then convert it)

Yours banding - more known as Moire, or Tonal pass - it is a matter of bit depth.
My solution is dodge and burn, and blur and noise.

Don't even think that 16bits will help you out with this...
I convert parts of the image or the whole thing to LAB because it is the easiest color space to solve problems in. As least a large part of them
I have never seen the operation of going from RGB to LAB and back make the problem worse so I don't worry about the small disturbance it creates. To say the truth LAB usually is of great help to me.

I think I am correct though on the term- banding, it is different from moire in my understanding. Moire we usually get on clothes were patterns don't go well with the pixel structure of the image. Moire we cope with quite well, especially that it usually happens on small areas.

16bit does sometimes help. We recently did a series of shots for reebok on white backgrounds. On some of the 8 bit files we began to get very delicate banding, which practically disappeared after redeveloping to 16bit.
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Old 12-08-2008, 02:07 AM
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stopa stopa is offline
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Re: banding... more complex the longer i work on t

Quote:
Originally Posted by tomasz.k View Post
I convert parts of the image or the whole thing to LAB because it is the easiest color space to solve problems in. As least a large part of them
to be honest I prefer Lab also

Quote:
Originally Posted by tomasz.k View Post
I have never seen the operation of going from RGB to LAB and back make the problem worse so I don't worry about the small disturbance it creates.
It occurs on wide gamut images.

Quote:
Originally Posted by tomasz.k View Post
I think I am correct though on the term- banding, it is different from moire in my understanding. Moire we usually get on clothes were patterns don't go well with the pixel structure of the image. Moire we cope with quite well, especially that it usually happens on small areas.
Yeap, you are right, but very often common people name this kind of bands a moire, and don't be startled when your client will say: "Hey, there is moire!" , and you will not understand what is he/she talking about.

Quote:
Originally Posted by tomasz.k View Post
16bit does sometimes help. We recently did a series of shots for reebok on white backgrounds. On some of the 8 bit files we began to get very delicate banding, which practically disappeared after redeveloping to 16bit.
Every case has its own solution.
Those images was finally printed or what?
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